Fuel pump governor



QL A

Nov. s, 1955 2,722,894v

R. J. IF IELD FUEL PUMP GOVERNOR Filed Jan. 24, 1950 2 Sheets-Sheet lNov. 8, 1955 R. J. [FIELD FUEL PUMP GOVERNOR 2 Sheets-Sheet 2 Filed Jan.24, 1950 N w i L2/U' eli/"bof eflfb'ei/ UnitedStates Patent O FUEL PUMPGOVERNOR Richard Joseph Itield, Dural, Australia, assignor to JosephLucas Limited, Birmingham, England Application January 24, 1950, SerialNo. 140,225

Claims priority, application Great Britain February 9, 1949 3 Claims.(Cl. 10S-162) This invention has for its object to provide an improvedfuel pump governor for regulating the supply of liquid fuel tojet-propulsion engines, gas turbines, or other prime movers.

The invention comprises in combination with a rotary fuel pump, a liquidfuel outlet, a liquid-operated servomechanism for regulating the rate ofsupply of liquid fuel from the pump to the outlet, a vent valve forcontrolling the servo-mechanism, a spring loaded movable member foractuating the vent valve in response to the action of opposed liquidpressures which are respectively correlated with the speed of the pumpand the pressure of the liquid fuel supplied by the pump to the outlet,a passageway for conducting to one side of the said member liquid fuelat a pressure correlated with the speed of the pump, a second passagewayfor conducting to the other side of the said member liquid fuel at apressure correlated with that at which the fuel is supplied to theoutlet, a restricted outlet in communication with the second passageway,and an adjustable throttle in the second passageway for determining theliquid fuel pressure exerted on the last mentioned side of the saidmember.

In the accompanying drawings:

Figures 1 and 2 are part sectional side elevations illustrating twoembodiments of the invention.

Referring to Figure 1, this illustrates an application of the inventionto a rotary liquid fuel pump A of the swashplate type and of knownconstruction. The pump comprises a rotor a mounted in a hollow body partb. Liquid fuel is supplied to the body part from a supply source throughan inlet connection at c leading to a suction port d. Liquid isdischarged by the pump through a port e leading to an outlet connectionat f. In the rotor a are formed a plurality of bores each containing areciprocatory plunger g which at its outer end co-operates with aswash-plate 20. During rotation of the rotor each bore receives liquidfuel from the port d and later the liquid is discharged by the plungerthrough the outlet f. For varying the strokes of the plungers and hencethe output of the pump, the obliquity of the swash-plate 20 is varied bya liquid-operated servo mechanism B of known form, and incorporated withthe pump body part. This mechanism consists of a piston h slidable in acylinder z' and loaded by a spring j. From the piston extends a rod kfor actuating the swash-plate 20. One end of the cylinder z' is incommunication with the discharge port e and the other end is incommunication with the same port through a restricted orifice mcontained in a passage n. The latter end of the cylinder alsocommunicates by way of a passage o with the seating p of a vent valve,the latter comprising a closure member q carried by a lever r. When theclosure member q of the vent valve'is closed, the liquid pressures inthe two ends of the cylinder are equal, and the spring j moves thepiston h to the right for increasing the obliquity of the swash-plate20, and thereby increasing the pump output, the swash-plate being shownin its position of maximum obliquity. But when the closure member q ofthe vent valve is opened, it relieves the liquid pressure in the lefthand end of the cylinder i, and the predominating liquid pressure thenexisting in the right hand end of the cylinder moves the piston h to theleft for reducing the obliquity of the swash-plate 20, and therebyreducing the pump output.

In carrying the invention into effect as shown in Figure l, there isformed in the body part a a chamber s which contains the above mentionedvent valve and lever, the chamber being bounded on one side by aflexible diaphragm twhich is attached to one end of the lever r.

The chamber s communicates with the pump inlet connection by Way of apassage u containing a restricted orilice v. Also the said chambercommunicates with the pump delivery passage by way of a passage w whichcontains an adjustable throttle x.

At the outer side of the diaphragm tis formed another chamber 2 by meansof a cover piece 3, this chamber being in communication with the portionof the pump body part containing the rotor a by way of a passage 4. Alsothe cover piece 3 is adapted to accommodate a spring 6 which at one endis attached to the diaphragm and which at the other end is attached toan adjustable anchorage 7 carried by the cover piece.

In this example it is desired that one side of the diaphragm shall besubject to a liquid pressure related to the speed of rotation of thepump rotor a, the latter deriving its motion from the prime mover towhich fuel is supplied by the pump. To meet the said reqmrement, therotor is provided (in known manner) with a passage 8 leading from anaxial bore 9 in the rotor to the region around the rotor, the bore 9being supplied with liquid from the pump inlet c. Due to the centrifugalaction of the rotor on the liquid in the passage 8, this liquid isdischarged to the said region and thence along the passage 4 to-theouter side of the diaphragm t at a pressure which is related to the rateof rotation of the rotor a.

With the arrangement above described, the diaphragm t is subject at itsopposite sides to two liquid pressures satisfying the requirements ofthe invention, the one pressure being related to the speed of rotationof the pump rotor (which in turn is related to the speed of the primemover which actuates the pump), and the other being related to thepressure of the liquid supplied by the pump. The latter pressure (whichis a fraction of the pump delivery pressure) is determined by the sizeof the orifice v and the setting of the throttle x. ln this respect itwill be seen that the throttle x controls the admission of liquid fuelto the chamber s, whilst the restricted orice v controls the dischargeof liquid fuel from this chamber. Consequently, the liquid pressure inthe chamber s depends on the ratio of the throttle opening and therestricted orifice as well as the pump delivery pressure, and (due tothe discharge through the restricted oriiice) is only a fraction of thepump delivery pressure. It will be appreciated that the pump deliverypressure is considerably greater than the pressure related to the speedof the pump rotor. Consequently, it is necessary for the pressure in thechamber sto be only a fraction of the pump delivery pressure, and thisis attained in a simple and satisfactory manner by the orifice v and thethrottle x.

The arrangement is such that when the pressure in the chamber 2 exceedsthat in the chamber s by a predetermined amount (which is variable bythe adjustment of the spring 6), the lever r is actuated for opening theassociated vent valve, so causing the servo mechanism to reducecorrespondingly the pump output.

In the above described example, the liquid pressure in the chamber sopposes liquid flow through the vent valve when the closure member q isopen. However, such opposition to the liquid flow through the vent valvecan be avoided, if desired, by employing the arrangement shown in Figure2 in which the liquid pressure in the chamber s is the same as that atthe pump inlet d. In this example, a double diaphragm consisting of apair of interconnected diaphragms t, t1 of different diameters ordifferent effective areas is used, the by-passed liquidbeing conveyed totheregion t2 between the diaphragms by the passage w which extendsthrough the diaphragm t1 at t4. The pressure of the liquid supplied tothe region between the diaphragms is variable` by a throttle x and alsoby an adjustable spill valve 10; The spill valve 10 leads to the chambers at. a position in the passage w between the throttle x and the regiont2 separating the diaphragms so that the liquid pressure in this regionis only a fraction of the pump delivery pressure. The chamber s is inthis example open by way of an unobstructed passage u to the inlet sideof the pump, the above mentioned restricted orifice v (Figure 1) being.omitted. In other respects the example shown in Figure 2 is similar tothat shown in Figure 1.

. Having. thus described my invention what I claim as new. and desire tosecure by Letters Patent is:

l. A governor for a rotary liquid fuel pump comprising in combinationwith the pump, a liquid fuel outlet, a liquid-operated servo-mechanismfor regulating the rate of supply of liquid fuel from said pump to saidoutlet, a vent valve for controlling said servo-mechanism, a springloaded movable member for actuating said valve in response to the actionof opposed liquid pressures which are respectively correlated with thespeed of said pump and the pressure of the liquid fuel supplied by saidpump tosaid outlet, a passageway for conducting to one side of saidmember liquid fuel at a pressure correlated with the speed off saidpump, a second passageway for conducting to the other side of saidmember liquid fuel at a pressure correlated with that at which the fuelis supplied to said outlet, a restricted outlet in communication withsaidsecond passageway, and an adjustable throttle inA said secondpassageway for determining the liquid fuel. pressure exerted on the lastmentioned side of said member.

2. A governor for a rotary liquid fuel pump comprising incombinationwith the pump, a liquid fuel outlet, a liquid-operatedservo-mechanism for regulating the rate of supplyr of liquid fuel fromsaid pump to said outlet, a hollow body part, a movable member containedin said body part and responsive to the action of opposed liquidpressures which are respectively correlated with the. speed ofI saidpump and the pressure of the liquid fuel supplied by said pump to saidoutlet, a vent valve operable by said member for controlling saidservomechanism, a spring acting on said member, a'. chamber situated atone side of said member and containing said vent valve, a passageway forconducting to the side of said member remote from said chamber liquidfuel at a pressure correlated with the speed of said pump, a secondpassageway for conducting to said chamber liquid fuel at a pressurecorrelated with that at which fuel is supplied to said outlet', anadjustable throttle in said second passage for determining the fuelpressure in said chamber, and a third passageway leading from saidchamber and provided with a restriction.

3. A governor for a.rotary liquid fuel pump comprising in combinationwith the pump, a liquid fuel outlet, a liquid-operated servo-mechanismfor regulating the rate of supply ofli`quid` fuel from said pump to saidoutlet, a hollow body part, a pair of spaced and interconnected movablemembers contained in said body partand responsive to the action ofopposedliquid pressures which are: respectively correlatedwith thespeed. of said pump and the pressure of liquid fuel supplied by saidpump tosaidoutlet,. avent valve operable by said membersfor controlling.said servo-mechanism, a spring acting on said members, a chambersituated at one side of said members and containing said vent valve, apassageway for conducting to the side. of said members remote from saidchamber. liquidfuely at a pressure correlated with the speed of saidpump, a. second passageway for conducting to the region between saidmembers liquid fuel at a pressure correlated with that at which the fuelis supplied to-said outlet, an adjustable throttle in said secondpassageway for determining the fuel pressure in the region betweensaidmembers, ar spill valve affordingy restricted communication betweensaid second passagewayand said chamber, and av third passageway leadingfrom said chamber.

References Cited in the file of this patent UNITED STATESPATENTS2,407,013 Ield Sept. 3, 1946 2,424,035- Iield'v V Iuly l5, 19472,429,005 Watson' et al. Oct. 14, 1947 2,442,954 Lee June 8, 19482,451,055; Beacham Oct. 12, 1948 2,581,276 Mock Ian. 1, 1952 FOREIGNPATENTS 959,467 France Oct. 3,' 1949

